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Re: Computer Shuts off, Stays Off

On Thu, 4 Oct 2007 08:28:47 -0500, "Jack B"

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Do you need all those PCI slots?  If so, get a full ATX
board with nForce2  chipset.  If not, it opens up the
opportunities for nForce2 mATX  also.  All nForce2 support
DDR333, all are socket A, and AGP.  Main question is where
you want to buy it, if you're willing to spend the time you
might get it cheaper, but only so much time is reasonable to
spend.  The typical good brands are MSI, Asus, Gigabyte,
Abit...  though as I'd mentioned, my shuttle MN31N still
works so I don't consider it too bad either, and I have a
Biostar M7NCG nForce2 board that has also held up better
than I'd expected it to, though it's bios is a bit buggy
with a wierd memory quirk requiring it not be  set to CAS3
for the memory... it's actually more stable at CAS2.5  even
when the modules are CAS3 rated.

Re: Computer Shuts off, Stays Off

Jack B wrote:
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The best fit, would be to find another Nforce2 motherboard.
This is your previous motherboard (AN35/N Ultra). You may
find something on Ebay.

The problem is, there aren't a lot of S462 boards left at retail.
So you don't get the best boards any more, just the low end

This is what Newegg has left. Chipset is SIS746FX.

PC CHIPS M848A (V5.0) A (462) SiS 746FX ATX AMD Motherboard  $55

A 2500+ is FSB333 (166Mhz clock times 2). That fits the Newegg
description OK. This is the table I use for Athlons and speed ratings.

The Radeon 7000 AGP pictured here, has both slots cut in the connector,
so it looks like a universal AGP card. That will plug into the
1.5V slot on the PC Chips board. And the link confirms
that the 7000 AGP would work with SIS746.

(Picture of Radeon 7000 AGP...)

More info on mixing and matching video cards and chipsets is here.
Just so you can verify this is OK yourself.

The only problem with a PCChips board, is the odds that it will work
properly when you get it. Have a look at the customer reviews, as there are
a couple hundred here, and that will give you some idea what to

Pricewatch will give you some idea as to what other boards are left at retail.
You can check the sellers via

This is the rating for (2.5 out of 10). Not a good rating.

Whatever board you get, you'll need to do a Repair Install of
Windows, and that will give you an opportunity to load in some
new drivers.

OK, final shot, is to go with a modern setup, and use built-in
graphics (i.e. ditch the 7000 and use a Geforce 6100 and its
built-in chipset graphics). The processor is quite cheap, and yet
should outperform the existing one by a slight bit.

    AMD Socket AM2 processor 3200+   $44

    CORSAIR ValueSelect 1GB (2x512MB) DDR2 SDRAM DDR2-533 (PC2-4200)  $33

    ASRock ALIVENF6G-VSTA AM2 NVIDIA GeForce 6100 or 6150SE / nForce 430  $55

The 1GB of RAM, is to make up for the use of built-in graphics, which
would use some of the system RAM. AM2 has dual channel capability, so
I spent an extra couple dollars and used a dual kit of memory. Total
price of the AM2 solution would be $132, and you could use your old
power supply. So the solution does cost more than the $55 for the
PCchips board. But you could have your choice of AM2 boards, and some
of the Gigabyte boards got good ratings in the Newegg list. They are
around $75, about $20 more than the ASRock I used as a placeholder above.


Re: Computer Shuts off, Stays Off

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Thanks - I will stew on this for a day or 2, and then probably buy the
Newegg PC Chips board.


Re: Computer Shuts off, Stays Off


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If he gets an nForce2 board, the odds are good there will be
no repair install needed, that it will boot Windows far
enough to plug-n-play any minor differences, and this
without any prior preparation to the OS.  Of course there
might still be a driver or two that needs installed.

Re: Computer Shuts off, Stays Off

Well, here is the latest on this thread, and no, I haven't solved the
problem yet.  I put in a new mb, PC Chips M848A, and also added a stick of
512 mem, doubling what was there.  I also have the new power supply in,
although, at this point, I don't think the original one was bad.  The result
of all that is that now the computer mostly does not turn on.  That is,
sometimes it does and sometimes it doesn't.  When it turns on, it stays on.
I have not hooked up the video or modem cards, HD, or Cd Rom yet.  Mostly,
when I press the on button nothing happens.  Occasionally, it does turn on,
but when I turn it off and then on, it stays off.  I've tried shorting the
power switch pins on the mb by hand, but nothing happens there either.

I'm at a loss, and don't know what to do now.

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Re: Computer Shuts off, Stays Off

Jack B wrote:
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These are the perils of home computer repair - a mounting pile of swapped
in hardware, as you try to narrow down the problem. Which is why my previous
posting, had an option to just bail on the Athlon.

If the fans twitch just for an instant, on the occasions when it fails
to turn on, then you know the motherboard is sending PN_ON# to the power
supply, so it actually tried to turn on. If it just "sits there", and there
is no response at all to pressing the computer case power button, then
you might suspect the motherboard is not sending PS_ON# at all. In that
case, it could be a bad power button on the computer front case, or since
this is a new motherboard, it could also be a motherboard defect.

OK, I have another test you can try. Try removing the processor from
the S462 socket (with power disconnected from the wall of course). Then
see if the power button can be used to reliably turn the power supply on
and off. Basically, you are testing motherboard, power supply, and computer
case front power button. If it seems to work better, without the processor
in there, then perhaps the processor is overloading things. But I'd really
expect to see a little bit of fan twitching or spinning, before Vcore
overcurrent trips and causes things to shut off.

If the motherboard has a LED that is connected to +5VSB, that should stay
lit and not blink. The +5VSB rail should be present and on solid, for as
long as the power switch on the back of the PSU is in the ON position.
If +5VSB winks out, that can prevent things from starting too. On motherboards
without a monitoring LED for +5VSB, you have one less feature to help with
the debugging.


Re: Computer Shuts off, Stays Off

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Thanks for the advice - here are a few more tidbits of info on things I've
tried or seen that may trigger something with somebody:

1)I've put an ohmmeter on the power switch wires and when I push the power
button, I do see a drop in resistance to 0, so I assume from that the power
switch is working.

2) I've replaced the power cord to the computer - no change.

3) With the computer plugged in, I measure 25 mv on the larger power
connectors in the pc (like the ones that plug into HD).  I don't know if
that's normal, but that's what I get.

4) When I press the power switch, the fans (2 fans - CPU fan plugged into mb
and case fan plugged into PSU connector) do not budge EXCEPT - sometimes
after I have pressed the on button and nothing has happened, a few seconds
later both fans move.  They don't move much, maybe a turn or 3, but they
definitely turn.  The first couple of times it happened, I thought I just
jostled something to cause that, but that is not it - they just turn by
themselves.  Maybe a capacitor is discharging or something - I don't know.
This has happened maybe 5 or 10% of the time I have pressed the switch.

5)My new mb does not have an LED lite, but the old one does.  I just plugged
the PSU into the old board, and the LED lite lit up.

6) I just removed the CPU and still no start.  So, now I have just the mb,
PSU connected to anything.

Any thoughts will be greatly appreciated.



Re: Computer Shuts off, Stays Off

On Tue, 16 Oct 2007 14:56:44 -0500, "Jack B"

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Yes, pin 9 to any common ground pin like 13.

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Yes, though I omitted that if you short 13-14 and it doesn't
come on, the next attempt should be attaching a small load
to 5V & 12V (ie - a hard drive) then trying again shorting

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Yes shorting 13-14 should turn the PSU on, sometimes it will
need an external load like the hard drive, and rarely a load
on 3.3V.  As for it being the equivalent of turning it on by
the power switch, the power switch through the board does
cause the same logical state of pulling the PS-On line low
to turn on the PSU as you do by shorting PS-On to ground,
but the scenario is different since the PSU has much less

It can't qualify the PSU as "good" but if it can't even do
that, it can show it is not functioning normally (usually
not correctly, but if we want to be strict/anal about the
specs, many PSU spec a minimal load per some rails that is
even higher than only one attached hard drive, but it is
very rare that only one HDD isn't enough to keep the PSU
running, even rarer a 3.3V load would also be needed).  

There are always some "ifs", "ands", and "buts"... for
example I have a PSU here that has failed and has correct
5VSB readings while unplugged from a motherboard, and it
comes on if PS-On is shorted to ground, but the 5VSB circuit
has failed to an instable state and so while connected to a
motherboard it can't turn a system on.  It was an old PSU
though not new like yours, and a failed fan seems to be the
initial cause.

Re: Computer Shuts off, Stays Off

On Thu, 18 Oct 2007 10:43:44 -0500, "Jack B"

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Assuming the old PSU also had the HDD (& CDROM) connected
when it shuts off, it does seem it is also bad.

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Yes this seems the best next step.

Re: Computer Shuts off, Stays Off

On Tue, 16 Oct 2007 09:14:41 -0500, "Jack B"

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1)  Unplug AC power from the PSU.

2)  Unplug everything (really, everything) from the
motherboard.  No CPU, no video, no memory, no front panel

3)  Double-check to be sure you don't have an extra standoff
on the motherboard tray that might be shorting out the back
of the board.  A commonly overlooked stray standoff might be
on the left row (looking inside an ATX chassis) 2nd from the
bottom.  Some boards have this mounting stud hole,
(including mATX and some ATX) and other ATX don't.

4)  Take the battery out and check it's voltage.  Check for
a battery insulator behind it (a piece of plastic).  Check
the Clear CMOS jumper to ensure it's in the normal/running
position.  Even if it is, now clear CMOS.

5)  Check the PSU input 110/220 voltage switch to ensure
it's correct per your location.

6)  Plug AC back into PSU, turn PSU rear switch on if so

7)  Use multimeter to measure 5VSB voltage.  You'll need
needle  probes to insert into the back of the ATX connector.
If these are not available, unplug AC, unplug PSU from mobo,
plug AC in and then measure 5VSB voltage from the pin-side
of the connector.

8)  Plug PSU back into mobo, plug AC back into PSU.

9)  Attempt to power on system by shorting the mobo's PS-On
pin to the (adjacent?) ground pin.  Does the PSU fan spin,
even ever so slightly the moment you short the PS-On pin to
ground?  If yes, measure voltages.  If no, try plugging in
something putting a 12V load on the system like a hard
drive, then try again to power on system.  If no still,
measure the power-good pin through the connector back while
shorting the mobo PS-On pin to ground.  You may have to use
your 3rd arm to do this.

10)  If no luck yet, disconnect PSU from mobo, connect PSU
only to a few hard drives.  Short it's PS-On pin to ground
pin and see if it comes on.  If it does, measure voltages.
If it does not, take a small ohm resistor (approx 10 Ohm,
2W+ rated) and put that between a 3.3V PSU pin and a ground
pin.  Most PSU don't need this 3.3V load but I mention it to
be more thorough.  Retry to turn on PSU shorting PS-On to

11)  If the PSU came on, stayed on, and during that the
output voltages looked acceptible, I would speculate that
you are very unlucky and the new PCChips board is defective
and the old board died from the PSU failure... but just for
kicks, whichever board you used to try the above steps, now
lather rinse and repeat using the other board, then one of
the other PSU with both boards.  That should keep you busy
till you don't give a damn anymore if it works or not.  ;-)

Re: Computer Shuts off, Stays Off

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I've tried most of what you suggested above, and got some interesting
results, I think.

No stray standoffs, batt voltage was 2.91 V, no insulation behind it, cmos
was set for normal, so I set for clear and replaced jumper to normal, PSU is
set for 115.

Now for the rest:  Both the original and new PSU show 5 V at 5VSB pin.  The
new PSU would not start when shorting pins anywhere with or without HD and
CDRom loads.  (I didn't try the 10 ohm resistor thing)  However, the old PSU
does start when I short the proper pins, but it does not stay on - it runs
for maybe 5 seconds and stops.

So, now I'm thinking/hoping that maybe the original PSU was the problem all
along, and the new one I bought from Circuit City happened to be defective,
meaning the original mb may be ok and I'll be able to return the new one to
Newegg.  Anyway, I am off to CC to return the PSU.

Any suggestions will be appreciated.


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